Force 50 HELP!

msullivan5

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Feb 16, 2015
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I have a 1989 Force 50 Model #507L9B. I checked compression end of last season and it was 120 in both cylinders. Now it is 120 in #1 and 60 in #2. The motor will not start UNLESS I remove #2 plug then it runs fine in the tank. If I put #2 plug in it will not start.
I had the boat out a few times this year and it ran ok--just a little hard to start--fresh water only.
First, any idea why #2 has gone bad?
Do I need to rebuild the motor or could it be a head gasket?
How long would a rebuild take? I have rebuilt a couple of car engines years ago but not a boat.
Any insights would be very appreciated.
 

RCO

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Jun 15, 2016
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Pull the head to see what is going on. May get lucky and just need a gasket. If you do end up having to rebuild it is a very simple engine to do, although parts cost will probably exceed the value of the motor.
 

msullivan5

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Feb 16, 2015
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Thank you RCO. I pulled the head this morning--the gasket was fine.
You sound like you have some experience, so just how "easy" would it be to do the rebuild? #2 piston is pretty sloppy but the cylinder looks ok with no scoring.
 

RCO

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You really should see some visible reason for the compression loss. Stuck or broken rings usually. The last one I totally rebuilt was a 91, it took about 4 hours start to finish. Parts were still available from the dealer at that point, and were around $400 jobber cost. The Force/Chrysler motors are very simple and you don't need many special tools to work on them.
 

RCO

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It is a pretty straight forward job if you have any experience with engines. Follow the directions, keep everything clean, and torque to the specs. One tip-make sure you count the needle bearings and get them all in, since they are not caged. Assembly lube will help hold them in place. Also go slow removing the exhaust cover bolts. May need heat, penetrating oil and patience to get them out without breaking.
 

jerryjerry05

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One maybe 2 or 3 hints: don't remove the exhaust chest cover unless reallllly needed.
​99% of the time nothing in there to fix unless your getting water in a cylinder.

You'll need a 1/4in 12point socket to remove the rod caps.

But like RCO suggested figure out WHY it went bad??
Use assembly lube and not regular grease(rco)

Bad: carb not set right, the fuel recirc system and lines clogged.
Plugged elbows??
Bad reeds.
Timing off.
Not enough oil?

One thing to do is remove the transfer port side covers on the cylinders and check for piston skirt damage.

Good luck with the rebuild.

Oh yea ASK questions a lot.
Take lots of pics during disassembly.
 

msullivan5

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Feb 16, 2015
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Thanks JJ. But HOW do I figure out why it went bad?
Where/what is the "elbow" and "reeds"?
Can I get assembly lube from a pep boys or auto zone or is that marine store stuff only?
Timing is OK and no water in cylinders.
If the carb was not set right or timing off would it run on just #1 with #2 plug removed?
Will start the disassembly tonight and chip away over the next few days. Not real big on the picture front but not afraid to ask questions as you can see.
Appreciate your willingness to assist.
 

jerryjerry05

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Assy. lube can be bought at any marine parts store or Napa.The elbow are at the end of the hoses on the motor

The reeds are under the carb.
While didassebling the reeds will be found in the intake.
Not necessarily on the carb.
Pics help when re-assembling cause sometimes you forget.
 

msullivan5

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Feb 16, 2015
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Following the manual but only find five (5) bolts holding the power head on. Most are toward the back of the motor. Seems like there should be a couple more up toward the transom but... Manual talks about 6 bolts. Is there one hiding under the exhaust side?
Looking from the underside I see a bolt head on each side but can't get to them--kind of wedged between the (cowling?) and the motor itself.
Any help?
 

jerryjerry05

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Gotta remove the cowl.
​There are 2 shock mounted bolts that need to be removed.
 

msullivan5

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Feb 16, 2015
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JJ do you know how to remove the cowling? Looks like I'd have to take it off the boat to do that. I can see two bolts one on each side between the cowling and the phead but no room to get in there to get 'em.
 

jerryjerry05

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Been so long that I'm not sure how??
​Just remembered it needs to be done.
 

msullivan5

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Feb 16, 2015
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On my model can't remove cowling. And YES, there are only five bolts in the engine compartment holding the power head in place. There are four nuts outside that also must be removed but only five, NOT SIX like the manual says under the cover. Took some time and prying but it finally broke free. Appreciate the input.
BTW found the issue, one of the roller bearings from the cam wore through the cage and one of the rings failed. Don't know which was the chicken and which was the egg. Cylinder bore was not in bad shape amazingly.
 
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